cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A259212 A total of n married couples, including a mathematician M and his wife W, are to be seated at the 2n chairs around a circular table. M and W are the first couple allowed to choose chairs, and they choose two chairs next to each other. The sequence gives the number of ways of seating the remaining couples so that women and men are in alternate chairs but M and W are the only couple seated next to each other.

Table of values

n a(n)
1 0
2 0
3 0
4 6
5 72
6 1920
7 69120
8 3402000
9 218252160
10 17708544000
11 1773002649600
12 214725759494400
13 30941575378560000
14 5231894853375590400
15 1025881591718766182400
16 230901375630648602880000
17 59127083048250564931584000
18 17091634972762948947148800000

List of values

[0, 0, 0, 6, 72, 1920, 69120, 3402000, 218252160, 17708544000, 1773002649600, 214725759494400, 30941575378560000, 5231894853375590400, 1025881591718766182400, 230901375630648602880000, 59127083048250564931584000, 17091634972762948947148800000]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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